1. Field of the Invention
The present invention relates to an ophthalmic apparatus and a corneal surgery apparatus used in ophthalmic clinics and the like.
2. Description of Related Art
On ophthalmic diagnosis, examination, treatment and prescription, it is sometimes necessary to obtain information about the position and/or shape of a pupil. For example, in corneal surgery for correcting refractive power by ablating a cornea with a laser beam, it is common practice to align a reference axis of irradiation of the laser beam with the position of a pupil center.
In addition, among multifocal contact lenses, in which different lens diopters are provided in the form of concentric circles around an axis of an optical center of the lens, there are some in which the axis of the optical center is decentered with respect to the geometric center of the lens. The amount of the decentering is determined in consideration of the pupil center position.
By the way, in the above-mentioned corneal surgery, a surgeon performs surgery in a well-lighted surgery room while observing a patient's eye illuminated with visible light. In this case, the patient's eye is in photopia (photopic vision) (i.e. the pupil of the eye is constricted), and the laser-beam irradiation is performed in alignment with the pupil center position in photopia. However, there are some cases where the pupil center position in photopia is not necessarily equal to that in scotopia (i.e. the pupil of the eye is dilated) according to individual circumstances. Conventionally, the differences (variances) between the pupil center position in photopia and that in scotopia are not taken into account. Therefore, the laser irradiation based on the pupil center position of the eye in photopia tends to cause a halo or glare when the eye is in scotopia.
Also, when designing a multifocal contact lens as described above, it has not been taken into account that the pupil center position in photopia is different from that in scotopia.